1. Field of the Invention
The present invention relates to a nonaqueous electrolyte battery, a battery pack using the nonaqueous electrolyte battery and a vehicle using the nonaqueous electrolyte battery.
2. Description of the Related Art
When a charge-discharge cycle of battery is repeated under such a large current, for example, exceeding 5 C, the cycle performance of the battery deteriorates more than in the case of charge-discharge cycle under a current of 1 C due to heat generation of the battery itself. A method in which the resistance of a battery is reduced to suppress the heat generation of the battery has been carried out so far as shown in, for example, JP-A 2001-102033 (KOKAI). However, even if any measures are taken to promote lowering of resistance, the following problem cannot be solved. That is, the heat generation of the battery is increased if current becomes large and the large-current cycle performance deteriorates.
On the other hand, a nonaqueous electrolyte secondary battery described in JP-A 2005-93077 (KOKAI) uses an electrode coiled body formed by winding a laminate of a positive electrode, a negative electrode and two types of separators. JP-A 2005-93077 (KOKAI) discloses a method in which a first separator having an air permeability of 180 sec/100 cm3 or more is disposed on the outside periphery of the negative electrode and a second separator having an air permeability of 120 sec/100 cm3 or less is disposed on the inside periphery of the negative electrode, in order to avoid over charge and thermal runaway of the battery at the time of abnormal heating.